A lithography is used to form fine patterns required for the production of LCD (Liquid Crystal Display) and LSI (Large Scale Integration), and a photoresist is used for the lithography. As the photoresist, there are a positive working type photoresist and a negative working type photoresist. Since the positive working type photoresist is particularly excellent in the dimensional accuracy and the resolving power, the positive working type photoresist is generally used.
An aqueous solution of an inorganic alkali or an organic alkali is used as a developer for the positive working type photoresist, but to prevent the occurrence of staining with an alkali metal, an aqueous organic alkali solution, in particular, an aqueous solution of tetramethylammonium hydroxide (TMAH) is suitably used and the content thereof at use is low as about 2.4% by weight. However, the content of an aqueous solution of tetramethylammonium hydroxide produced as an undiluted developer solution is usually from about 5 to 40% by weight and hence it is necessary at use to dilute the undiluted developer solution with pure water.
Now, for correctly forming fine patterns, it is important to develop the light-exposed resist with good accuracy and it is necessary for this purpose that the composition of the developer used is strictly controlled to a definite content.
Hitherto, the content and the composition of the developer are correctly controlled by a developer maker and the developer is prepared by the developer maker and supplied to users such as LSI makers and LCD makers. Considering that the content of an alkali which is the main component of the developer is about 2.4% by weight as described above but when the undiluted developer solution is obtained as an aqueous solution having a content of from about 5 to 40% by weight, there is a problem that when the developer maker supplies the diluted developer solution to users, the costs for the container and the transportion for transporting the developer from the developer maker to the users increase. To overcome this problem, the developer maker supplies the undiluted developer solution to users and users may dilute the undiluted developer solution. However, it is necessary that the content of the developer after dilution is strictly adjusted to a definite content and the developer is kept and controlled at the content, and also from the standpoint of the industrial practice, it is required to practice the above procedure quickly and with labor-saving.
Even under these circumstances, a developer preparing apparatus and a developer preparing method, which can strictly adjust the content of the developer at a definite value and keep and control the content of the developer, and also can practice the procedure quickly and with labor-saving have not yet been realized.